The above picture is from Sina Weibo, showing May 23rd, 2019 as a very cool "Prime Day". That is, not only that the corresponding number of the date 20190523 is a prime, but all its sub-strings ended at the last digit 3 are prime numbers.

Now your job is to tell if a given date is a Prime Day.

Input Specification:

Each input file contains one test case. For each case, a date between January 1st, 0001 and December 31st, 9999 is given, in the format yyyymmdd.

Output Specification:

For each given date, output in the decreasing order of the length of the substrings, each occupies a line. In each line, print the string first, followed by a space, then Yes if it is a prime number, or No if not. If this date is a Prime Day, print in the last line All Prime!.

Sample Input 1:

20190523

Sample Output 1:

20190523 Yes
0190523 Yes
190523 Yes
90523 Yes
0523 Yes
523 Yes
23 Yes
3 Yes
All Prime!

Sample Input 2:

20191231

Sample Output 2:

20191231 Yes
0191231 Yes
191231 Yes
91231 No
1231 Yes
231 No
31 Yes
1 No

分析：

看起来真的非常easy，而且这个字符串最长8位都没有超出int的范围~

代码：

#include<bits/stdc++.h>
using namespace std;
int isprime(int n){
	if(n==1) return 0;
	for(int i=2;i*i<=n;i++)
		if(n%i==0) return 0;
	return 1;
}
int main(){
	string str;
	cin>>str;//输入8位日期 
	int cnt=0;
	for(int i=0;i<8;i++){
		string s=str.substr(i);
		printf("%s ",s.c_str());
		if(isprime(stoi(s))){
			cnt++;
			printf("Yes\n");
		}else printf("No\n");
	}
	if(cnt==8) printf("All Prime!");
	return 0; 
} 

测试： 

实际上也非常easy，希望明天的题都是这样的（ziwoanwei~）